E-Prop. Still a good choice?

[SkyrangerRich]

Hi,

I haven’t posted here in a while, but I’m still about and still managing to squeeze time for flying in around my kids!

My 2006 CTSW still has its original Warp Drive prop fitted, but it’s looking very tatty now, has some decent chunks out of it. It needs replacing. 
 

The Warp Drive is the only prop certified/approved for the CTSW in the UK, so any alternative has to go through the approval process, which is a pain, but not impossible. It has to be fixed pitch/ground adjustable. 
 

When I looked into this a while ago, the French E-prop was getting great reviews on the CT. Is it still the best choice? It would be easier for me to get a replacement Warp Drive, but I’m OK with going through the process if the e-prop is noticeably better. 
 

E-prop have quoted this specification, does it seem correct?

For CTSW Rotax 912S reducer 2.43 TITANIUM Leading Edge Protection Diameter: 170 cm / 66.9 inch

The E-prop appears to be a lot lighter than my Warp Drive. Are there any CoG issues with this?

Many thanks,

Rich

[Roger Lee]

Of the 14 props I tested years ago the Warp Drive was the worst in climb. Not too bad in cruise. Bad if you have a prop strike with it.

[FlyingMonkey]

Others may disagree, but I think the E-Props is the current best choice for the CTs.  The performance is excellent, and the weight is far lower than a Neuform, Warpdrive, or Sensenich...to the tune of 5-8 pounds less off the nose.  Plus if you operate off of grass, dirt, or other unpaved strips the edge protection on the E-props is better than all the others except Sensenich (which has Stainless Steel edge protection).

IIRC the Warp is the least performant of the prop choices out there, so changing to an E-props should give you both climb and cruise improvements.  It certainly did for my airplane when I replaced the Neuform.

EDIT:  Also...the E-props repair situation is very simple...every prop is balanced and the blades matched at the factory.  If you ding a blade and need a new one, you can give them the blade serial number and they'll ship you one that is balance matched and a drop in replacement.  Same for the Spinner which is also factory balanced.

[FlyingMonkey]

3 minutes ago, Roger Lee said:

Bad if you have a prop strike with it.

I thought Warps were the easiest to repair though...just fill with epoxy and sand it out to the correct contour.

[SkyrangerRich]

Thanks, think that’s decision made then. 
 

I’m surprised I get any thrust out of my Warp Drive at all, it’s in such bad shape it looks like it was used to chop bricks!

[Roger Lee]

3 hours ago, FlyingMonkey said:

I thought Warps were the easiest to repair though...just fill with epoxy and sand it out to the correct contour.

Because it is so rigid and hard if you have a prop strike it transmits more energy into the gearbox and crankshaft. A much bigger chance of crankshaft twisting. If you fly a lot out of back woods gravely terrain then it may be an okay choice as it can take more rocks and still fly. It can be repaired with epoxy. If you have short take offs over trees or short fields then the climb will suffer if you need to climb over obstacles.

[FlyingMonkey]

4 hours ago, SkyrangerRich said:

Thanks, think that’s decision made then. 
 

I’m surprised I get any thrust out of my Warp Drive at all, it’s in such bad shape it looks like it was used to chop bricks!

Wait until you see how narrow the E-Props blades are.  They look like they'd do nothing at all.

[SkyrangerRich]

Order is in. 
 

This will be first installation of an E-prop on a CT in the UK, so I’ll be required to do a test flight with a test pilot and 5 - 10 hours of endurance flying and performance statistics gathering. 
 

Would be much easier to get another Warp, but I’m quite excited to see the difference the prop makes. 

My only concern is that the E-prop is slightly longer than my Warp. I’ll lose about 1.5cm/0.6inch of ground clearance. 

Can someone confirm this is the correct spec: 

For CTSW Rotax 912S reducer 2.43 TITANIUM Leading Edge Protection Diameter: 170 cm / 66.9 inch

Thanks for your help. 

[Bill3558]

Blades are so sharp I wear gloves to burp the engine. 

[Anticept]

5 hours ago, SkyrangerRich said:

Order is in. 
 

This will be first installation of an E-prop on a CT in the UK, so I’ll be required to do a test flight with a test pilot and 5 - 10 hours of endurance flying and performance statistics gathering. 
 

Would be much easier to get another Warp, but I’m quite excited to see the difference the prop makes. 

My only concern is that the E-prop is slightly longer than my Warp. I’ll lose about 1.5cm/0.6inch of ground clearance. 

Can someone confirm this is the correct spec: 

For CTSW Rotax 912S reducer 2.43 TITANIUM Leading Edge Protection Diameter: 170 cm / 66.9 inch

Thanks for your help. 

It should be a DUR-3-170-C4-T for both CTSW and CTLS

[SkyrangerRich]

7 hours ago, Anticept said:

It should be a DUR-3-170-C4-T for both CTSW and CTLS

Lovely, thanks. 

[FlyingMonkey]

13 hours ago, Bill3558 said:

Blades are so sharp I wear gloves to burp the engine. 

I agree, they are very thin on the edges!

[SkyrangerRich]

20 hours ago, FlyingMonkey said:

Wait until you see how narrow the E-Props blades are.  They look like they'd do nothing at all.

What’s the science behind it? I’m going to get asked as soon as it’s in the hangar. 

Less frontal area, less drag?

[FlyingMonkey]

1 hour ago, SkyrangerRich said:

What’s the science behind it? I’m going to get asked as soon as it’s in the hangar. 

Less frontal area, less drag?

No science, just sorcery.  

Yeah, I think it's all in the blade twist with different AoA at various points along the length of the blade.  Lower drag for sure.  There are some technical explanations on the E-Props website.

[Anticept]

Remember that high aspect ratio is extremely efficient. Glider wings are very long and skinny.

[procharger]

Did my e prop today its perfect great results> CTSW

[SkyrangerRich]

My E-prop arrived this week. Great service from the guys in France, about two weeks from ordering to delivery. Will be starting the form filling and inspection process to have it certified ASAP. 
 

It’s a lovely thing, the blades are incredibly light! Spinner is larger than I expected!

My current warp drive is set for 5500wot. I fly with slightly faster aircraft (an Alpi Pioneer 300 and a 130hp Sonex) so I’d welcome any additional cruise speed that I can get from the E-prop. What have people found are the optimum settings? I’ve got to admit, optimising props is a dark art to me!

[GrassStripFlyBoy]

E-Props recommended 26.1 for my SW, I settled in at 26.8 and it's right on 5500 both static and max cruise.  I've not flown a warp drive, suspect you'll be very pleased with the change.

[Jim Meade]

E-Props recommends 5500 WOT +_50 as optimal.

But optimal for what?  Climb?  Cruise speed?  Compromise?  Would the CTSW fly faster at 5500 if the prop was pitched for 5650 WOT than if it was pitched for 5500?  I thought in my case that happened, but I got tired of fiddling and ended up with 5540 WOT one time and just left it there.  Maybe when it is warmer outside I'll fiddle with it some more.

Maybe someone can cite a reference as to the prop's performance at 5500 based on various WOT settings.  Actually, I typically cruise at about 5200 or so when just bumming around. 

[Jacques]

5 hours ago, SkyrangerRich said:

My E-prop arrived this week. Great service from the guys in France, about two weeks from ordering to delivery. Will be starting the form filling and inspection process to have it certified ASAP. 
 

 What have people found are the optimum settings? 

you will end up between 26 & 27...roughly...  and  depending on the weather (pretty humid where you are ) and how cold it is. you may end up with a 'summer pitch' and a 'winter pitch' 

here a -10 C , i will need to reduce the pitch ...but not sure I will bother ..for just few hours in winter

winter flights are short and low, while summer flights much higher...and longer

also, from a Warp Drive to the E-props, we gain 8mph @5000 rpm [ but, not on a CT ]

[GrassStripFlyBoy]

4 minutes ago, Jacques said:

you may end up with a 'summer pitch' and a 'winter pitch' 

I understand your points, and agree.  My thoughts are the CT's are such a high performing bird leave it at the summer pitch, in winter when air is more dense they still jump off the ground.  

[Jacques]

yep,   but SkyrangerRich is in the UK winter for the next months. Is ' summer pitch ' will be to discover ...next year

so,  in the 'lower 26 ' would be my suggestion...  

my 2 cents

[Jim Meade]

Jacques, what is your target RPM and do you vary that between seasons?

 

[SkyrangerRich]

All really good info, thanks all. I will aim for 26.5 for my first go and see where that gets me in terms of RPM at WOT.

 Do we agree with 5500 or is a little higher better? Isn’t 100% power at 5800?

I hope you all have a wonderful Christmas and New Year. 

[Anticept]

Engine power and useable thrust are two different things, follow the prop manufacturer's instructions, they tell you what the recommended pitch and power settings are.

Over or underpitching a prop, even if the engine runs at 5800rpm, doesn't mean you get the additional power to useful thrust. You'll probably lose efficiency.